In some conventional plasma cutting systems (e.g., Hypertherm™ Long Life™ plasma arc cutting systems), a plasma arc is typically initiated during a pre-flow gas flow state and then switched to a cut-flow gas flow state for cutting a workpiece (e.g., a plate-like workpiece). This process is typically performed because the gas flow conditions used for proper and reliable plasma arc ignition are often different from those used during steady state cutting conditions. A valve assembly (e.g., an off-valve assembly) located relatively close to the torch is typically used to switch between ignition and steady state cutting. For example, the off-valve assembly typically includes a manifold and several valves (e.g., solenoid valves) to control plasma gas flow and shield gas flow to the torch. For either plasma gas flow or shield gas flow, there are typically two valves for controlling the gas flow. For example, one valve can be dedicated specifically for pre-flow gas flow, and the other valve can be dedicated specifically for cut-flow gas flow.
In some other plasma cutting systems (e.g., Hypertherm non-Long Life plasma cutting systems), substantially all of the gas control functions (i.e., gas control valves) are located in a power supply or a gas console to which the torch is connected, which can be located 20 to 150 feet away from the torch.